Solenoid-operated valve for thermally insulated piping and attachment construction therefor

ABSTRACT

The present invention relates to a solenoid-operated valve for a thermally insulated piping having a thermally insulated outer periphery suitable for transporting low-temperature fluid, high-temperature fluid or the like and relates also to an attachment construction for the valve. 
     Conventionally, with this type of solenoid-operated valve for a thermally insulated piping, since it is necessary to to increase a magnetic flux density of the solenoid coil by increasing the number of turns of the oil or the electric current to be applied thereto, there has been the problem of high production costs and running costs. 
     In the case of the solenoid-operated valve for a thermally insulated piping according to the present invention, inside a heat-insulating layer (6) surrounding flow passages (7, 20, 21, 26, 33) in the form of a pipe, there is provided a fixed core (23) constituting a magnetic circuit between a solenoid coil (17) and a movable coil (18). Then, magnetic resistance between the solenoid coil and the movable core may be reduced, without entailing enlargement of the movable core and the production costs and the running costs may be reduced.

TECHNICAL FIELD

The present invention relates to a solenoid-operated valve for athermally insulated piping having a thermally insulated outer peripherysuitable for transporting low-temperature fluid, high-temperature fluidor the like and relates also to an attachment construction for thevalve. The invention relates more particularly to a solenoid-operatedvalve for a thermally insulated piping and to an attachment constructionfor the same, said valve including a solenoid coil disposed outside aheat-insulating layer surrounding flow passages, a movable core disposedinside the heat-insulating layer to be reciprocated along a longitudinaldirection of the flow passages in response to amagnetizing/demagnetizing action of the solenoid coil and a valve memberdisposed inside the heat-insulating layer to open or shut the flowpassage in response to the reciprocating movement of the movable core.

BACKGROUND ART

According to the above-described solenoid-operated valve for a thermallyinsulated piping, a solenoid coil is disposed outside a heat-insulatinglayer which surrounds flow passages in the form of a pipe, and insidethe heat-insulating layer, there are provided a movable core and a valvemember operable to open or shut the flow passage in response to areciprocating movement of the movable core. Then, the valve memberdisposed inside the heat-insulating layer may be opened or shut inassociation with a magnetizing/demagnetizing action of the solenoidcoil, while restricting heat conduction from the inside to the outsideof the heat-insulating layer. According to the conventional art, amagnetic circuit is comprised solely of the movable core disposed insidethe heat-insulating layer to be movable in response to amagnetizing/demagnetizing action of the solenoid coil (for example, seeJapanese laid-open patent gazette Sho. 61-252984).

For this reason, the magnetic resistance between the solenoid coil andthe core is large. Then, in order to allow the movement of the movablecore associated with magnetization of the solenoid core to take place ina reliable manner, it is necessary to increase the magnetic flux densityby increasing either the number of turns of the coil or the electriccurrent, thus resulting in problem of high production costs or highrunning costs.

In order to solve this problem, it is conceivable, for instance, toprovide the movable core with a sufficient length in the longitudinaldirection of the flow passage, thereby to minimize the magneticresistance between the solenoid coil and the movable core. In this case,however, as the movable core is enlarged, the load needed for itsmovement is increased as well. As a result, just like the aforedescribedconventional art, for the reliability of movement of the movable core,it becomes again necessary to intensify the magnetic flux density of thesolenoid coil by increasing the number of turns or the value of electriccurrent to be applied thereto.

The present invention attends to the above-described state of the art,and an object of the invention is to provide a solenoid-operated valvefor a thermally insulated piping and its attachment construction, whichallow reduction in the production costs and running costs throughingenious arrangement of an interior construction of the heat-insulatinglayer.

DISCLOSURE OF INVENTION

For fulfilling the above-noted object, in the above-describedsolenoid-operated valve for a thermally insulated piping, theconstruction according to the present invention is characterized in thatinside the heat-insulating layer there is provided a fixed coreconstituting a magnetic circuit between the solenoid coil and themovable core.

The above-described construction achieves functions and effects asfollow.

The magnetic resistance between the solenoid coil and the movable coremay be reduced, without entailing enlargement of the movable core.Accordingly, the production costs or running costs may be reduced.

With the solenoid-operated valve for a thermally insulated pipingaccording to the present invention, said valve member, said movable coreand said fixed core may be held inside said heat-insulating layer in amanner allowing integral attachment thereto.

With this construction, since the valve member, the movable core and thefixed core are held inside the heat-insulating layer in a mannerallowing their integral attachment thereto, the assembly operations ofthe valve member, the movable core and the fixed core inside theheat-insulating layer may be advantageously simplified.

According to the characterizing features of an attachment constructionfor a solenoid-operated valve for a thermally insulated piping relatingto the present invention, in an attachment construction for asolenoid-operated valve for a thermally insulated piping in which asolenoid coil is disposed outside a thermally insulated pipe having flowpassages surrounded by a heat-insulating layer and the thermallyinsulated pipe accommodates therein a valve mechanism including a valvemember operable to open or shut said flow passage in response to amagnetizing/demagnetizing action of said solenoid coil, said attachmentconstruction is characterized in that said valve mechanism is fixed to aconnecting end of a connecting member detachably connected andcommunicated with a pipe end portion of said thermally insulated pipeand that said valve mechanism fixed to said connecting member isinserted from said pipe end portion of the thermally insulated pipe intothe interior of this thermally insulated pipe.

With this construction, the valve mechanism fixed to the connecting endof the connection member may be inserted from the pipe end portion ofthe thermally insulated pipe into the interior of this thermallyinsulated pipe to be attached therein; and the valve mechanism may bewithdrawn from the interior of the thermally insulated pipe by detachingthe connecting member from the thermally insulated pipe.

As a result, this attachment construction of a solenoid-operated valvefor a thermally insulated pipe may advantageously facilitate theattaching operation of the valve mechanism into the thermally insulatedpipe axed maintenance and inspection operations of the valve mechanismattached inside the thermally insulated pipe.

The valve mechanism may be detachably fixed to the connecting end of theconnecting member.

If the valve mechanism is detachably fixed to the connecting end of theconnecting member as described above, the valve mechanism which has beenwithdrawn from the interior of the thermally insulated pipe may bedetached from the connecting member.

As a result, the maintenance and inspection operations of the valvemechanism may be further facilitated. And, moreover, the valve mechanismmay be readily replaced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a section view of a piping construction employing asolenoid-operated valve fur a thermally insulated piping relating to oneembodiment of the present invention,

FIG. 2 is an enlarged section view of major portions of FIG. 1construction in a condition where a solenoid coil is not supplied withelectric power,

FIG. 3 is an enlarged section view of the major portions of FIG. 1construction where the solenoid coil is supplied with electric power,

FIG. 4 is a section view taken along a line IV--IV of FIG. 1,

FIG. 5 is a section view taken along a line V--V of FIG. 1, and

FIG. 6 is an exploded view showing an attachment construction for thesolenoid-operated valve for a thermally insulated piping.

BEST MODE FOR CARRYING OUT THE INVENTION

FIGS. 1 through 3 show a construction of piping for transporting liquidnitrogen incorporating a solenoid-operated valve C at a connectingportion between transport pipes A, B for transporting liquid nitrogen toa location where the liquid nitrogen is to be used or to a reservoirtank or the like.

The transport pipes A, B are formed of a stainless steel (SUS316L)having a relatively low relative permeability and are provided as adouble-pipe construction in which an inner pipe 4 and an outer pipe 5are welded to pipe-end fittings 1, 2. Between the inner pipe 4 and theouter pipe 5, there is formed a vacuum type heat-insulating layer 6which surrounds flow passages 7, 20, 21, 26, 33 in the form of tubes. Alarge-diameter receiver hole 8 communicating with the upstream-side flowpassage 7 is formed on an inner periphery of a terminal end of theupstream-side transport pipe A, and a small-diameter insert portion 9provided on an outer periphery of a terminal end of the downstream-sidetransport pipe B is inserted into the receiver hole 8. Then, thetransport pipes A, B are fixedly connected to each other by means of acap nut 10 threaded with the pipe-end fitting 1.

The receiver hole 8 is formed by welding a large-diameter inner pipe 13to a small-diameter inner pipe 11 via a joint fitting 12 and weldingthis large-diameter inner pipe 13 to the pipe-end fitting 1. The insertportion 9 is formed by welding a small-diameter outer pipe 18 to alarge-diameter outer pipe 14 via a joint fitting 8 and welding thissmall-diameter outer pipe 15 to the pipe-end fitting 2.

The solenoid-operated valve C includes a plunger 18 formed of thestainless steel (SUS408) having a relatively high relative permeabilityand acting as a movable core to be reciprocated in the longitudinaldirection of the flow passages in association with amagnetizing/demagnetizing action of a solenoid coil 17. The solenoidcoil 17 wound about a resin bobbin 18 and a yoke 22 having asubstantially `C`-shaped radial section into which inner periphery thesolenoid coil 17 together with the bobbin 18 are fitted are outwardlyand fixedly engaged, in the form of a doughnut-like arrangement, on anouter peripheral face of the large-diameter outer pipe 14 outside theheat-insulating layer 6. The solenoid-operated valve further includes avalve seat member 28 defining an orifice 27 communicating with thedownstream flow passage 26, a valve member 19 made of resin and operableto open or close the orifice 27 in response to the reciprocatingmovement of the plunger 18, and a fixed core 23 made of the samematerial as the plunger 18 and constituting a magnetic circuit betweenthe solenoid coil 17 and the plunger 18. And, these components 18, 28,19 and 23 are attached on the inner peripheral side of thelarge-diameter inner pipe 13 inside the heat-insulating layer 6. Theplunger 18 defines flow passages 20, 21, and the fixed core 23 defines aflow passage 33 communicating the flow passages 20, 21 with the upstreamflow passage 7.

The valve mechanism 34 is provided as a unitary construction forallowing unitary attachment of this mechanism into the receiver hole 8.Then, in this mechanism 34, the fixed core 23 and the valve seat member28 are weld-fixed to each other via a guide cylinder 30 made of astainless steel (SUS316L) having a relatively low relative permeability,and the plunger 18 is attached inside the guide cylinder 30 to bereciprocatable along an inner peripheral face of the guide cylinder 30in the direction of the pipe axis. Further, the valve member 19 retainedagainst withdrawal by a press fitting 31 is attached at the downstreamend portion of the plunger 18 to be axially reciprocatable. As shown inFIG. 6, the valve seat member 28 is detachably threaded, via a gasket29, to the pipe-end fitting 2 of the thermally insulated pipe B actingas a connecting member to be detachably attached to and communicatedwith the pipe end portion of the thermally insulated pipe A, thereby tobe integrally fixed to the transport pipe B. Then, in this condition, asthe mechanism 34 together with a seal ring 24 is inserted from the pipeend portion of the thermally insulated pipe A into the receiver hole 8of this thermally insulated pipe A, the valve mechanism 34 may bereadily attached into the thermally insulated pipe A.

A coil spring 25 is provided for urging the plunger 18 in the directionaway from the fixed core 23, and a further coil spring 32 is providedfor urging the plunger 18 and the valve member 19 away from each other.Then, when the solenoid coil 17 is supplied with no electric power, asshown in FIG. 2, the valve member 19 closes the orifice 27 by the urgingforces of the coil springs 25, 32. When the pressure inside thedownstream flow passage 26 builds up above a predetermined value, thevalve member 19 opens the orifice 27 against the urging forces of thecoil springs 25, 32.

When electric power is supplied to the solenoid coil 17 to magnetize thesame, as shown in FIG. 3, the plunger 18 is moved to the upstream sideby a stroke D against the urging force of the coil spring 25 and thevalve member 19 opens the orifice 2, whereby the upstream flow passageand the downstream flow passage 26 become communicated to each other viathe flow passage 33 defined in the fixed core 23 and the flow passages20, 21 defined in the plunger 18.

OTHER EMBODIMENTS

(1) The solenoid-operated valve for a thermally insulated pipingaccording to the present invention may comprise a pilot controlledsolenoid-operated valve, in addition to the direct-acting typesolenoid-operated valve.

(2) The solenoid-operated valve for a thermally insulated pipingaccording to the present invention may be connected to a transportpiping for transporting a high-temperature fluid such as hot water,vapor or the like, in place of a low-temperature fluid such as liquidhydrogen, liquid helium, freon or the like.

(3) The movable core moved in response to a magnetizing/demagnetizingaction of the solenoid coil may be provided integrally with the valvemember.

(4) The type of the heat-insulating layer surrounding the flow passagesis not 1 imited to the vacuum type heat-insulating layer. Instead, thelayer may comprise such material as foamed urethane or the like.

What is claimed is:
 1. A solenoid-operated valve for a thermallyinsulated piping, said valve comprising:flow passages; a heat-insulatinglayer surrounding said flow passages; a solenoid coil disposed outsidesaid heat-insulating layer; a movable core disposed inside saidheat-insulating layer to be reciprocated along a longitudinal directionof said flow passages in response to a magnetizing/demagnetizing actionof said solenoid coil; a valve member disposed inside saidheat-insulating layer to open or shut said flow passage in response tosaid reciprocating movement of said movable core; and a fixed coreinside said heat-insulating layer, said fixed core constituting amagnetic circuit between said solenoid coil and said movable core. 2.The solenoid-operated valve of claim 1, wherein said valve member, saidmovable core and said fixed core are positioned inside saidheat-insulating layer in a manner allowing integral attachment thereto.3. The solenoid-operated valve of claim 1, wherein said movable coreincludes a plunger formed of stainless steel having a relatively highrelative permeability.
 4. An attachment construction for asolenoid-operated valve for a thermally insulated piping, saidconstruction comprising:thermally insulated pipe having a flow passagetherein surrounded by a heat-insulating layer; a connecting memberdetachably connected and communicating with a pipe end portion of saidthermally insulated pipe; a solenoid coil disposed outside saidthermally insulated pipe; and a valve mechanism accommodated within saidthermally insulated pipe, said valve mechanism including a valve memberoperable to open and shut said flow passage in response to amagnetizing/demagnetizing action of said solenoid coil, wherein saidvalve mechanism is fixed to a connecting end of said connecting member,and wherein said valve mechanism is inserted from said pipe end portionof said thermally insulated pipe into the interior of said thermallyinsulated pipe.
 5. The attachment construction for a solenoid-operatedvalve of claim 4, wherein said valve mechanism is detachably fixed tosaid connecting end of said connecting member.
 6. The attachmentconstruction for a solenoid-operated valve of claim 4, wherein saidheat-insulating layer comprises a vacuum type heat-insulating layersurrounding said flow passage.